Many studies from the original proposal have been dropped, and the project has been streamlined. It is difficult to resist being overly ambitious, as was true of the original submission, when proposing five years of experiments from a large and productive research team that is excited about our collaborative opportunities, both among ourselves and with the other investigators in this program who are studying complementary phenomena. On the one hand, the rhesus monkeys tested in these studies complete, as a group, almost 100,000 trials per week across tasks and studies, providing an ample foundation for the present investigations as well as the studies proposed by other researchers in this program. Similarly, this project team tested an average of over 500 undergraduate volunteers per year in the last four years. We certainly want to generate the most science possible across the proposed 5-year funding period. On the other hand, we acknowledge that the more studies that are described in a single proposal, the less clear the details of those studies can be, the less coherent the proposal appears, and the harder it becomes to see the theme that ties the studies together. In organizing the remaining experiments, we have sharpened our construct definitions by ensuring that the tasks in Study 1 reflect the control of attention (selection of some stimuli rather than others) for processing. There is of course a longstanding debate regarding whether attention is selection of stimuli for processing (early selection), or selection of a response (late selection). In light of the reviewers' comments, we avoided this debate in the present proposal by choosing early-selection tasks (tests of how well individuals select some stimuli and ignore others). We moved response-selection tasks, together with other tests of cognitive control, into Study 2. Several very interesting cognitive tests related to executive functioning (including planning, monitoring, and statistical learning were deleted from Studies 2 and 3 so as to maintain theme of the control of attention across the project. Although we agree with the reviewer who described these tasks as clever and compelling, we also agreed with the reviewers who saw them as peripheral to the central theme. Study 3 was consequently refocused on the reciprocal role of attention and learning - which seems critical, given our desire to understand how learning establishes the experiential and executive constraints that vie for control over attention (i.e., of anchoring executive in behavior rather than allowing it to remain an undefined homunculus. This study also supports our translational effort to identify particular t3rpes of training (including symbol training) that might alter the control of attention. The net result of these reductions in experiments, together with the decision to move the details of the fMRI testing and analyses to the Core where they belong, provided space for elaborating on the brain-behavior experiments we will tackle during this funding period. We have attempted to show that it is timely to study these cognitive competencies using neuroimaging technologies. We have also added to the preliminary studies to build the foundation for this entire proposal. At the same time, we did add several experiments that were specifically recommended by the reviewers or by our review of the recent literature, including (a) a replication of two previous findings (Ei.i) using conditions that calibrate baseline performance levels across species; (b) addition of the eyes-looking task to complete the possible comparisons within the cognitive-control study E2.1; and (c) addition of CPT-AX testing to distinguish between proactive and reactive responding, consistent with a recent model of cognitive control. The results of Ei.i could potentially change the design of each subsequent experiment. In this revision, we believe that we've achieved a good balance by including the studies that have the greatest probability of addressing our specific aims, and by eliminating relatively uninformative or potentially redundant tests of specific populations or with specific measures. We recognize that one confusing element of the original proposal pertained to which participant groups would be tested on which specific studies. In part, this is a result of our desire to base those decisions on the results of earlier experiments. For example, we don't want to administer a task to children or chimpanzees until it has been shown to be a good task, in the sense of producing meaningful variations as a result of the independent-variable manipulations, in testing with undergraduate participants or monkeys. It is neither practical nor scientifically necessary to test every group (naive and experienced macaques, capuchins, chimpanzees, children, undergraduates with and without ADHD) on every task and condition. However, we want understand attention control from comparative, developmental, neuropsychological, and of course cognitive perspectives, and thus it is necessary to test multiple groups. Additionally, to control for the influence of different levels of motivation, training, and so forth, it is necessary to produce converging evidence by using multiple tasks.